54 BULLETIN 16 9, UNITED STATES NATIONAL MUSEUM 



In resume, there are 13 genera all of Paleocene aspect but con- 

 fined to this fauna and of little use in exact correlation. Of the eight 

 ■other genera confined to this fauna, four have their closest allies 

 in the Torre j on and four have their closest known allies in the Upper 

 Paleocene, but three of these here appear to be distinctly more primi- 

 tive than their Upper Paleocene relatives. Eight genera are other- 

 wise typical of the Torrejon, and these here include two species 

 indistinguishable from those of the Torrejon. The other species of 

 these genera are in most cases closel}^ allied to those of the Torrejon, 

 mostly without definite evidence of being more or less advanced, 

 but one may be less and one may be more specialized than the most 

 .comparable Torrejon species. Four genera are common to this fauna 

 •and to that of the Torrejon, but they also appear in later beds. Their 

 species are here generally closer to the Torrejon species and in two 

 cases appear to be identical. Two genera probably range nearly 

 ,or quite throughout the Paleocene, one of them here represented 

 by a typically Torrejon species, but one that does range into some- 

 what later beds. Five of the genera are otherwise known only in 

 Upper Paleocene (in some cases also ranging into later) beds, but in 

 each case the species here present is decidedly distinctive, and in no 

 «ase is a Middle Paleocene ancestor or close ally otherwise known. 



This evidence conclusively proves the fauna to belong to the 

 Middle Paleocene and to be close to the Torrejon in age. It does 

 not preclude a slight difference in age from the Torrejon, but dif- 

 ferences of facies and geographic position are adequate to explain the 

 faunal distinction without supposing the age to be different, and if 

 the age is slightl}^ different they obscure the evidence for this. There 

 is nothing suggestive of the Puerco. There is a greater resemblance 

 to the Upper Paleocene than is shown by the Torrejon fauna, but the 

 evidence suggests that this is largely or wholly due to the discovery 

 in this place and facies of forerunners of later groups not themselves 

 really later here than the Torrejon. 



The onl> other very closely correlatable horizon is that of the 

 Scarritt Quarry. The correlation has been discussed elsewhere 

 (Simpson, 1936b), where it was shown that the quarry fauna itself 

 is very close to that of the Tiffany in age but may be slightly earlier. 

 From a more general point of view, there is some suggestive but 

 inconclusive evidence strengthening the probability of slightly earlier 

 age for this than for the principal Tiffany horizon. The probable 

 occurrence of Tetraclaenodon at an even higher level, replaced in 

 the Tiffany and all later beds by the more advanced and possibly 

 descendant genus Phenacodus, weights the evidence in this direction, 

 as does also the occurrence at about this level of a specimen indis- 

 tinguishable from Anisonchus sedorius, a Torrejon species. The 

 .occurrence of Claenodon indistinguishable from the Torrejon C. ferox 



